Determine all x values

Question

x ∈ [0, 2π] such that

tan 2x + sec 2x = 1

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Answer 1

θ = 2x

tan θ + sec θ = 1

(sin θ / cos θ + (1 / cos θ) = 1

sin θ + 1 = cos θ for cos θ ≠ 0

θ = 0